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Transaction Simulation

Securely verify transactions in a real chain environment
Transaction Simulator can be self-hosted, if needed
Forget about network latency between node and app, add more security based on blockchain design and architecture, and get the same benefits as the SaaS version.
The transaction simulation mechanism allows you to execute the code in the EVM using the real state (you can specify either the latest block or any other). The transaction will not be recorded in the blockchain, but you will receive all the necessary data about its execution - such as detailed logs on diff state.
The simulation is implemented by calling the debug_traceCall method using the simulatorTransaction tracer.
Supported and Planned Chains
BNB Chain
Ethereum
Polygon
Query
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cURL Example
curl --location --request POST 'https://bsc-mainnet.rpcfast.com?api_key=*****' \
--header 'Content-Type: application/json' \
--data-raw '{
    "id":1,
    "jsonrpc":"2.0",
    "method":"debug_traceCall",
    "params": [
        {
            "from": "0x8626f6940E2eb28930eFb4CeF49B2d1F2C9C1199",
            "to": "0xC469e7aE4aD962c30c7111dc580B4adbc7E914DD",
            "gas": "0x38ec9",
            "data": "0xa9059cbb000000000000000000000000c469e7ae4ad962c30c7111dc580b4adbc7e914dd0000000000000000000000000000000000000000000000000000000000000001"
        },
        "latest",
        {
            "tracer": "simulatorTransaction"
        }
    ]
}'
The method accepts 3 parameters:
1.Object with truncation details
1.from - Address from
2.to - Address tp
3.gas - Gas limit in hex
4.data - Transaction Payload
2.Block hash or latest
3.Tracer specify (required parameter)
Response
Example response
{
    "jsonrpc": "2.0",
    "id": 1,
    "result": {
        "post": {
            "0x8626f6940e2eb28930efb4cef49b2d1f2c9c1199": {
                "balance": 7191999784037716435034,
                "nonce": 14
            },
            "0xc469e7ae4ad962c30c7111dc580b4adbc7e914dd": {
                "storage": {
                    "0x673de83553dc3a2c0f59aa7193de392a4530feb73b9d6cd4fcef68802b8195c1": "0x0000000000000000000000000000000000000000000000000000000005f5e0fe",
                    "0xfb05fe32b3c70ddd1ab6d1436c8058b66823efba374c166903d3ad4780ae2cd4": "0x0000000000000000000000000000000000000000000000000000000000000002"
                }
            }
        },
        "pre": {
            "0x8626f6940e2eb28930efb4cef49b2d1f2c9c1199": {
                "balance": 7191999784037716675176,
                "nonce": 13
            },
            "0xc469e7ae4ad962c30c7111dc580b4adbc7e914dd": {
                "balance": 0,
                "code": "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",
                "nonce": 1,
                "storage": {
                    "0x673de83553dc3a2c0f59aa7193de392a4530feb73b9d6cd4fcef68802b8195c1": "0x0000000000000000000000000000000000000000000000000000000005f5e0ff",
                    "0xfb05fe32b3c70ddd1ab6d1436c8058b66823efba374c166903d3ad4780ae2cd4": "0x0000000000000000000000000000000000000000000000000000000000000001"
                }
            }
        },
        "call": {
            "from": "0x8626f6940e2eb28930efb4cef49b2d1f2c9c1199",
            "gas": 211589,
            "gasUsed": 34306,
            "to": "0xc469e7ae4ad962c30c7111dc580b4adbc7e914dd",
            "logs": [
                {
                    "address": "0xc469e7ae4ad962c30c7111dc580b4adbc7e914dd",
                    "topics": [
                        "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef",
                        "0x0000000000000000000000008626f6940e2eb28930efb4cef49b2d1f2c9c1199",
                        "0x000000000000000000000000c469e7ae4ad962c30c7111dc580b4adbc7e914dd"
                    ],
                    "data": "0x0000000000000000000000000000000000000000000000000000000000000001"
                }
            ],
            "value": 0
        }
    }
}
Response resultobject contain few objects:
call - transaction execution results
from - Address from
to - Address to (can be contract address for contract operaions)
gas - gas limit for transaction defined by user
gasUsed - real gas usage value
value - eth value
logs - execution logs
address - contract address
topics - event optics
data - log payload
pre / post - State before/after transaction(s) execution
<address> - address, used in transaction
balance - balance in Wei
nonce - nonce
code - hex-encoded bytecode
storage - storage slots of the contract
Multiple transactions simulation
Sometimes it is necessary to execute several transactions in a row, taking into account the changes made to the state by each transaction. For this, we have developed debug_traceCallMulti method.
It works almost exactly like debug_traceCall, only instead of a single object, it accepts an array of objects of the same format.
cURL Example
curl --location --request POST 'https://bsc-mainnet.rpcfast.com?api_key=***' \
--header 'Content-Type: application/json' \
--data-raw '{
    "id":1,
    "jsonrpc":"2.0",
    "method":"debug_traceCallMulti",
    "params": [
        [
            {"from": "0xdfcec744c8417d2a0ef72fe520438dd20f368369", "to": "0xf508fcd89b8bd15579dc79a6827cb4686a3592c8", "gas": "0x38ec9", "data": "0xa0712d680000000000000000000000000000000000000000000000001a4ca49dff654641"},
            {"from": "0xdfcec744c8417d2a0ef72fe520438dd20f368369", "to": "0xf508fcd89b8bd15579dc79a6827cb4686a3592c8", "gas": "0x38ec9", "data": "0xa0712d680000000000000000000000000000000000000000000000001a4ca49dff654641"}
        ],
        "latest",
        {
            "tracer": "simulatorTransaction"
        }
    ]
}'
The response will also be an array of data, in the same order in which the objects were arranged in the request:
{
    "jsonrpc": "2.0",
    "id": 1,
    "result": [...]
}
Example requests
Block timestamp override
curl --location 'https://bsc-mainnet.rpcfast.com?api_key=***' \
--header 'Content-Type: application/json' \
--data '{
    "id":1,
    "jsonrpc":"2.0",
    "method":"debug_traceCall",
    "params": [
        {"from": "0x8626f6940E2eb28930eFb4CeF49B2d1F2C9C1199", "to": "0x62DB6c1678Ca81ea0d946EA3dd75b4F71421A2aE", "gas": "0x38ec9", "data": "0xa9059cbb00000000000000000000000062db6c1678ca81ea0d946ea3dd75b4f71421a2ae0000000000000000000000000000000000000000000000000000000000000001"},
        "latest",
        {
            "tracer": "simulatorTransaction",
            "blockOverrides": {
                "time": 1692185198
            }
        }
    ]
}'
Block number override
curl --location 'https://bsc-mainnet.rpcfast.com?api_key=***' \
--header 'Content-Type: application/json' \
--data '{
    "id":1,
    "jsonrpc":"2.0",
    "method":"debug_traceCall",
    "params": [
        {"from": "0x3f349bBaFEc1551819B8be1EfEA2fC46cA749aA1", "to": "0x0000000000000000000000000000000000001000", "gas": "0x38ec9", "data": "0xf340fa010000000000000000000000003f349bbafec1551819b8be1efea2fc46ca749aa1"},
        "latest",
        {
            "tracer": "simulatorTransaction",
            "blockOverrides": {
                "number": "0x1d9a583"
            }
        }
    ]
}'
Coinbase address override
curl --location 'https://bsc-mainnet.rpcfast.com?api_key=***' \
--header 'Content-Type: application/json' \
--data '{
    "id": 1,
    "jsonrpc": "2.0",
    "method": "debug_traceCall",
    "params": [
        {
                "from": "0x26EeDf987b1d7e160EFC252878A2C0980BD91504",
                "to": "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
                "gas": "0xec724",
                "gasPrice": "0x63782218b",
                "value": "0x5af3107a4000",
                "data": "0xd0e30db0"
            },
        "latest",
        {
            "tracer": "simulatorTransaction",
            "blockoverrides": {
              "coinbase":"0xaeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef"
            }
        }
    ]
}'
Support
Last modified 3mo ago